Shrinking stretched cellulose acetate fibers with diethyl ketone



Patented July 18, 1950 SHRINKING STRETCH-RED CELLULOSE ACE- TATE FIBERS WITH DIETHYL KETONE Donald Finlayson and Albert William Mortimer Cooke, Spondon, near Derby, England, assignors to Cola-nose Corporation of America, a corporation of Delaware No'DraWing. Application October 2, 1947," Serial No. 777,598. In Great Britain October 15, 1946 2 Claims.

This invention relates to the treatment of textile materials and in particular to processes involving the shrinking of textile materials comprising fibres (e. g. staple fibres or continuous filaments of yarns or fabrics containing such fibres.- or filaments) having a basis of an organic derivative of cellulose, especially cellulose acetate.

A- number-of different agents have been proposed for shrinking fibres having a basis of celluloseacetate, amon the most important being methylene chloride. This agent, although frequently preferred to others, has certain disadvantages; thus it needs to be considerably diluted in order-to prevent it exerting too great a softening action on the materials; it has a high vapour pressure at ordinary temperatures; its recovery is attended with some dificulty; and, like most chlorinated hydrocarbons, it is toxic.

According to the present invention textile materials comprising fibres having a basis of an organic derivative of cellulose are shrunk by means of a composition comprising diethyl ketone.

In an important application of the invention yarns having a basis of a lower fatty acid ester of cellulose, especially cellulose acetate, which have been stretched, as described for example in prior U. S. application S. No. 4,511, filed Febru-- ary- 1, .1035, now abandon-ed, and U. S. Patents Nos. 2,142,909 and 2,142,912, especially yarns which have been stretched in an atmosphere of wetsteam, are shrunk by means of a composition comprising diethyl Ketone.

The diethyl ketone may be used in association with another compound having a similar or greater shrinking action on the cellulose derivative material, e. g. a latent solvent for the cellulose derivative such, for example, as methylene chloride or ethylene chloride. (The term latent solvent denotes a compound which is capable of swelling the cellulose derivative to a high degree and which, while not itself a solvent for the cellulose derivative, forms with certain other compounds which also are not solvents for the cellulose derivative, especially alcohols, mixtures which are capable of dissolving the cellulose derivative.) A number of examples of substances having a shrinking action on materials having a basis of an organic derivative of cellulose are given in U. S. Patent No. 2,058,422.

Preferably however the diethyl ketone is employed at an elevated temperature in the absence of substantial proportions of other liquids having a shrinking action of the cellulose derivativ'e. The temperature required depends on the particular cellulose derivative of which the yarns or other materials are made, the degree of shrinkage required, and the extent to which the yarns have previously been stretched in a softened condition. Generally speaking, it is preferable to treat cellulose acetate unstretched yarns, and yarns which have been stretched :by up to about 3 times their original length, at temperatures above 0., especially between about and C;; at higher temperatures, e. g. temperatures of about 05 C., such yarns are shrunk to a very high degree, but their tenacity is greatly reduced. Cellulose acetate yarns which have been stretched by more than 3 times their original length are preferably treated at higher temperatures, thus yarns stretched by 7 or more times their original length may be subjected to the action of the diethyl ketone at temperatures above 80 (3., especially between and C. The lustre of unstre'tch'ed yarns and yarns that have been stretched by up to about 3 times is sometimes reduced in the shrinking operation, especially at temperatures above 70 (3., but yarns that have been stretched by '7 or more times retain their brightness even at temperatures as high as 100 C. Yarns having basis of another lower fatty acid ester of cellulose may be treated under similar conditions.

As already indicated, diethyl ketone may be used in processes involving the shrinking of either stretched or un'stretched yarns having a basis of an organic derivative of cellulose and especially of cellulose acetate, and of other textile materials comprising such yarns. Its shrinking action on unstretched yarns is, under the same conditions, considerably greater than its action on highly stretched yarns of the same initial denier and composition. The use of diethyl ketone is particularly valuable when it is desired to shrink yarns to a very high degree without causing the individual filaments in the yarns to fuse together. This property of diethyl ketone is illustrated by the fact that no mutual adhesion of the filaments occurrs even when the yarns are shrunk to the highest degree possible, e. g. up to about 80% in the case of cellulose acetate yarns that have been stretched to about 2 or 3 times their original length, and up to 45 or 50% in the case of unstret-ched cellulose acetate yarns. With shrinking agents comprising a substantial proportion of methylene chloride it is not possible to produce such a high degree of shrinking without causing the filaments to coalesce to a considerable extent.

or After being shrunk the fibres or textile materials containing them may be freed from the diethyl ketone, for example by washing with a suitable solvent, e. g. petrol or a somewhat higher boiling hydrocarbon composition. .Since diethyl ketone has little or no action on cellulose acetate materials at ordinary temperatures, it is not necessary to take special steps to remove the diethyl ketone from the materials as soon as the desired degree of shrinking has taken place, but it is sufficient to allow the materials to cool to a temperature below about 50 C. or 30 C., e. g.

to ordinary room temperature, and subsequently to remove the diethyl ketone therefrom at any convenient time.

The invention is illustrated by the following examples Example 1 A 225 denier cellulose acetate yarn was immersed for 30 minutes in a bath of diethyl ketone at a temperature of 70 C. The yarn was then removed from the bath and washed with petrol.

It had undergone a shrinkage of 32% and its extensibility had been increased from 28.5% to i The yarn had become opaque.

Example 2 A cellulose acetate yarn which had been stretched to twice its original length was immersed for 15 minutes in a bath of diethyl ketone at a temperature of 70 C. and was then removed from the bath .and washed with petrol. Its ex-. tensibility had been increased from 8.2% to 12.2 and the appearance of the yarn remained substantially unchanged. At 75 C. the yarn was shrunk by 14% and its extensibility was increased to 13.8%.

Example 3 A cellulose acetate yarn which had been stretched to ten times its original length was immersed for 15 minutes in a bath of diethyl ketone at a temperature of 90 C. It was then cellulose.

cellulose acetate fibres, it is also of value in core nection with fibres having a basis of other organic esters of cellulose, for instance cellulose propionate and butyrate and mixed esters such as cellulose acetate butyrate and cellulose acetate stearate, and also with fibres having a basis of a cellulose ether, for instance ethyl or benzyl In general fibres having a basis of cellulose ethers or cellulose esters of fatty acids with more than seven carbon atoms in the molecule require somewhat more vigorous conditions than fibres having a basis of a cellulose ester of a lower fatty acid.

Having described our invention, what we desire to secure by Letters Patent is:

1. Process for increasing the extensibility of yarns made up of a number of separate continu ous filaments having a basis of cellulose acetate, which yarns have been stretched to more than '7 times their original length, which comprises imrriersing a textile material comprising the said yarns in diethyl ketone at a temperature of -100 C. until the yarns have shrunk to a substantial extent.

2. Process for increasing the extensibility of yarns made up of a number of separate continuous filaments having a basis of cellulose acetate, which yarns have been stretched to more than '7 times their original length, which comprises immersing a textile material comprising the said yarns in diethyl ketone at a temperature of REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,058,422 Dickie et a1 Oct. 27, 1936 2,065,125 Dreyfus Dec. 22, 1936' 2,072,250 Dreyfus Mar. 2, 1937 2,072,251 Dreyfus Mar. 2, 193'? 2,031,173 Dreyfus May 25, 1937 OTHER REFERENCES Coltofz' J. Soc. Chem. Ind., Oct. 1937, pages 367T, 378T. 

1. PROCESS FOR INCREASING THE EXTENSIBILITY OF YARNS MADE UP OF A NUMBER OF SEPARATE CONTINUOUS FILAMENTS HAVING A BASIS OF CELLULOSE ACETATE, WHICH YARNS HAVE BEEN STRETCHED TO MORE THAN 7 TIMES THEIR ORIGINAL LENGTH, WHICH COMPRISES IMMERSING A TEXTILE MATERIAL COMPRISING THE SAID YARNS IN DIETHYL KETONE AT A TEMPERATURE OF 85*-100*C. UNTIL THE YARNS HAVE SHRUNK TO A SUBSTANTIAL EXTENT. 